The Drug Resistance Strategies Project is a culturally grounded, school-based drug prevention program of research funded by NIDA since 1989. The proposed project seeks to extend our research on ethnicity and drug use through a multidisciplinary collaboration among Penn State University, Arizona State University, and the schools in Phoenix, Arizona. The 5-year study will utilize the integration of the Ecological Risk and Resiliency Approach with Communication Competence Theory to (1) describe the development of ecological risk and resiliency factors among Mexican and Mexican American youth, (2) strengthen the effective multicultural intervention developed under the current grant by increasing the number of lessons to 12, comparing different ages of intervention (5th versus 7th grades), and testing an acculturation enhanced version of the curriculum designed for Mexican and Mexican American youth, and (3) examining the moderating effects of four ecological risk and resiliency factors (acculturation level, acculturation stress, ethnic identity, parental monitoring) on prevention efficacy. The multicultural intervention will be lengthened, and then an acculturation enhanced version developed. Next, both versions will be modified for the 5th grades. The proposed study will implement a pretest-posttest, control group design to test eleven hypotheses. 45 elementary and 37 middle schools (4350 students) in Phoenix, Arizona will be randomly assigned to one of seven conditions (control, 5th grade/Multicultural Intervention, 5thgrade/Acculturation Enhanced, 7th grade/Multicultural Intervention, 7th grade/Acculturation Enhanced, 5th& 7th grades/Multicultural Intervention, 5th & 7th grade/Acculturation Enhanced). Students will complete questionnaires both before and after the intervention in both the 5th and 7th grades, as well as once each year in the 6th, 8th, and 9th grades. These questionnaires request information about recent and lifetime substance use, substance use mediators (norms, expectancies, intentions, and resistance skills), and ecological risk and resiliency moderators (acculturation, acculturation stress, ethnic identification, and parental monitoring). Analyses will primarily use linear mixed models to test impacts of the intervention and the intervention enhancements on substance use and substance use mediators, and to examine the influence of the ecological risk and resiliency moderators on substance use over time and on the intervention.